Application of fuzzy logic to control traffic signals

FUZZY TRAFFIC SIGNAL CONTROLLER 
Now a days predetermined traffic lights are used under time of the day scheme to control traffic congestion. But it 
does not offer an optimum solution for the fluctuations of the traffic condition. A fuzzy logic control system 
provides a better optimal solution for the fluctuating traffic system. Controlling the traffic flow system using fuzzy 
technology has the ability to convert human thinking process into an algorithm using some mathematical models. 
Implementation of real rules which are similar to the way that traffic policemen would think to manage traffic signal 
lights can be done by fuzzy if-then rules. The traffic signal controllers are supposed to adjust the cycle time of green 
light signal depending upon the amount of vehicles arrival which would maximize the traffic flow and control the 
regular waiting time. The inputs of fuzzy signal control system are generated by the help of an experience. Fuzzy 
rule based system derives actions from given inputs by constructing if-then rules which represent the relation among 
the linguistic variables. In general, a fuzzy traffic signal controller will improve the traffic protection in the junction, 
usage of junction at its maximum level and minimize the delays. In a traffic light system red light indicates the 
arriving vehicles to be stopped, green light indicates the arriving vehicles to be allowed and the yellow light 
indicates the switch over of red light or green light. 
Figure 1: Fuzzy Traffic Signal Controller 
An layout of isolated four lane traffic junction is given 
 
 
Figure 2
:
 Layout of 
isolated four lane traffic junction
 
 
Fuzzification 
Defuzzification 
Signal
control
actions 
Traffic
situation